Structure for securing diaphragm, and diaphragm pump and valve device equipped with the same

1. A structure for securing a diaphragm to a case comprising:

the case composed of a first frame having a first concave portion defining a first chest, and a second frame having a second concave portion defining a second chest, and

the diaphragm separating the first chest from the second chest,

wherein

the first frame comprises a first frame main body and first securing portions,

the second frame comprises a second frame main body and second securing portions,

the first securing portions extend toward the second frame and are disposed along an outer circumference of the first frame main body at intervals so as to form third concave portions therebetween, and

the second securing portions extend toward the first frame and are disposed along an outer circumference of the second frame main body at intervals so as to form fourth concave portions therebetween,

wherein

the first frame and the second frame are fitted with each other in such a fit state that the first securing portions fit into the respective third concave portions, and the second securing portions fit into the respective fourth concave portions, whereby the first securing portions and the second securing portions are alternately disposed along the outer circumference of the case,

wherein

in the fit state, first pawls protruding from the first securing portions engage with the second frame, and second pawls protruding from the second securing portions engage with the first frame, whereby the fit state is retained, and

an edge portion of the diaphragm is compressed and held between the first frame and the second frame, whereby the diaphragm is secured to the case.

2. The structure as set forth in claim 1 , wherein each said first securing portion comprises

a first protruding piece being elastically deformable and extending toward the second frame from an outer edge of the first frame main body, and

the first pawl is provided in an end portion of the first protruding piece to engage with the second frame.

3. The structure as set forth in claim 2 , wherein each of the second securing portions comprises

a second protruding piece being elastically deformable and extending toward the first frame from an outer edge of the second frame main body, and

the second pawl is provided in an end portion of the second protruding piece to engage with the first frame.

4. The structure as set forth in claim 1 , wherein the edge portion of the diaphragm is provided with a thick part having a larger thickness than a central membrane part.

5. The structure as set forth in claim 4 , wherein the first frame and/or the second frame is provided with a positioning groove at which the thick part is disposed.

6. A diaphragm pump equipped with the structure as set forth in claim 1 wherein

the first frame is provided with a first port communicating with the first chest,

the second frame is provided with a second port communicating with the second chest,

a fluid for driving the diaphragm is fed to the first chest via the first port, and

a fluid being treated flows into and flows out of the second chest via the second port.

7. A valve device equipped with the structure as set forth in claim 1 wherein

the first chest of the first frame is provided with a driving means for driving the diaphragm,

the second frame has an inflow port for flowing the fluid into the second chest, and an outflow port for flowing the fluid out of the second chest, and

the outflow port has an opening around which a valve seat is formed, and

the diaphragm sits on and leaves the valve seat to close and open the outflow port.